ANTIBACTERIAL ACTIVITY OF DIOSQUINONE AND PLUMBAGIN FROM THE ROOT OF DIOSPYROS-MESPILIFORMIS (HOSTCH) (EBENACEAE)

Diosquinone and plumbagin isolated from the root of Diospyros mespilif ormis (Hostch), a common ingredient in several folk medicines and food s, have been shown to have antibacterial activity against a wide range of organisms. The minimum inhibitory concentrations (MICs) of diosqui none against Staphylococcus aureus NCTC 6571 and 5. aureus E3T ranged from 3 to 30 mu g/mL, while those against Escherichia coli KL16 and Ps eudomonas aeruginosa NCTC 6750 ranged from 15 to 16 mu g/mL. MICs were found to increase with the concentration of cells used in the inoculu m. Bacterial studies showed that S. aureus NCTC 6571 exhibited a parad oxical biphasic response to dioquinone in nutrient broth, whereas bact erial activity against E. coli KL16 increased with concentration up to the highest concentration of dioquinone tested. Activity against E. c oli KL16 was more pronounced in phosphate-buffered saline than in nutr ient broth. The other active compound isolated, the naphthoquinone plu mbagin, gave MIC values between 400 and 600 mu g/mL.